Updated dependencies. Added sample config. Tried improving some stuff

Cargo.toml

@@ -2,23 +2,24 @@
 name = "gandi-dns-updater"
 version = "0.1.0"
 authors = ["Vegard Berg <vgberg@gmail.com>"]
-edition = "2018"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-anyhow = "1.0.40"
-dirs = "3.0.2"
-nix = "0.20.0"
-serde = {version = "1.0.126", features = ["derive"]}
-serde_json = "1.0.64"
-toml = "0.5.8"
-trust-dns-resolver = "0.20.3"
-ureq = {version = "2.1.1", features = ["json"]}
-xdg = "2.2.0"
+anyhow = "1.0.71"
+clap = { version = "4.3.2", features = ["derive"] }
+dirs = "5.0.1"
+nix = "0.26.2"
+serde = {version = "1.0.163", features = ["derive"]}
+serde_json = "1.0.96"
+toml = "0.7.4"
+trust-dns-resolver = "0.22.0"
+ureq = {version = "2.6.2", features = ["json", "tls"]}
+xdg = "2.5.0"
 
 [profile.release]
 opt-level = 'z'
 lto = true
 codegen-units = 1
-panic = 'abort'
+panic = 'abort'

config.example.toml

@@ -1,6 +0,0 @@
-api_key = "YOUR API KEY"
-
-[[domain]]
-name = "YOUR DOMAIN"
-subdomains = ["@", "foo", "bar"]
-

config.sample.toml

@@ -0,0 +1,11 @@
+# api_key = "MY API KEY"
+# 
+# [[domain]]
+# name = "mydomain.com"
+# subdomains = ["www", "ftp"]
+# update_A = true        # Update IPv4 A record
+# update_AAAA = false    # Update IPv6 AAAA record
+# 
+# [[domain]]
+# name = "example.com"
+# subdomains = ["@", "www"]

src/config.rs

@@ -1,5 +1,7 @@
 use serde::{Deserialize, Serialize};
 
+const SAMPLE_CONFIG: &str = include_str!("../config.sample.toml");
+
 #[derive(Debug, Serialize, Deserialize, std::cmp::PartialEq)]
 pub struct Configuration {
     pub api_key: String,
@@ -30,28 +32,43 @@ fn bool_true() -> bool {
 }
 
 impl Configuration {
-    pub fn read_config() -> anyhow::Result<Configuration> {
+    /// Read the configuration file from the default configuration directory.
+    pub fn read_config(config_path: Option<&str>) -> anyhow::Result<Configuration> {
         use dirs::config_dir;
 
-        let conf_dir = {
-            // Get the user's config dir if it is not a system user.
+        let conf_dir = 'conf: {
+            if let Some(path) = config_path {
+                // If config path is explicitly passed, use it instead
+                break 'conf std::path::PathBuf::from(path)
+            }
+            // If running on Linux, try to get the user dir if UID >= 1000.
+            // Assume that it is a system/service user otherwise, and look for the
+            // global config file.
+            #[cfg(target_os = "linux")]
             if nix::unistd::getuid().as_raw() as u32 >= 1000 {
                 config_dir()
-                    .expect("Failed to get the user's config dir")
+                    .expect("Expected config dir")
                     .join("gandi-dns")
             } else {
                 std::path::PathBuf::from("/etc/gandi-dns")
             }
+            // If it is not a Linux system, just look for the user directory...
+            #[cfg(not(target_os = "linux"))]
+            config_dir()
+                .expect("Expected config dir")
+                .join("gandi-dns")
         };
 
         std::fs::create_dir_all(&conf_dir).expect("Failed to create config directory");
 
-        let config_str = std::fs::read_to_string(conf_dir.join("config.toml")).expect(&format!(
-            "Could not read config file at: {}",
-            conf_dir.join("config.toml").to_string_lossy()
-        ));
+        let config_str = std::fs::read_to_string(conf_dir.join("config.toml"))?;
 
         let c: Configuration = toml::from_str(&config_str)?;
         Ok(c)
     }
 }
+
+
+pub fn print_config() {
+    println!("{}", SAMPLE_CONFIG);
+}

src/main.rs

@@ -2,8 +2,25 @@ mod config;
 mod dns;
 mod gandi;
 
+use clap::Parser;
+
+#[derive(Debug, Parser)]
+#[command(author, version, about)]
+struct Args {
+    #[arg(short, long)]
+    config: Option<String>,
+
+    #[arg(long)]
+    print_template_config: bool,
+}
+
 fn main() -> anyhow::Result<()> {
-    let conf: config::Configuration = config::Configuration::read_config()?;
+    let args = Args::parse();
+    if args.print_template_config {
+        config::print_config();
+        return Ok(());
+    }
+    let conf: config::Configuration = config::Configuration::read_config(args.config.as_deref())?;
 
     let (ip4, ip6) = dns::get_ext_ip()?;